Process and composition for mechanical working of aluminum and aluminum alloys

ABSTRACT

Mechanical working of aluminium or aluminium alloys is carried out in the presence of a water-based cooling lubricant, which has the form of a stable solution and contains as lubricating and corrosion inhibiting agents a combination of (a) a carboxyl compound having a hydrophobic group of 7-14 carbon atoms and (b) a tertiary alkyl alkanol amine having a molecular weight of less than 300. The amounts of the carboxyl compound and the tertiary alkyl alkanol amine are chosen so that a base/acid equivalent ratio between the alkanol amine and the carboxyl compound is less than 1.0. A concentrate, which after dilution with water, may be used as a cooling lubricant is also disclosed.

Normally, kerosene-based cooling lubricants are used in the cold rollingof aluminum. However, kerosene-based cooling lubricants emitunacceptable quantities of hydrocarbons, pose a considerable firehazard, and give a low cooling effect, which restrict productioncapacity.

Accordingly, replacement of kerosene-based cooling lubricants bywater-based emulsions containing specific additives which reducecorrosion and/or the friction between the metal surface and the workingtool, especially at high pressures, has been proposed, inter alia, byKnepp et al U.S. Pat. No. 4,243,537, patented Jan. 6, 1981 and EPOpatent application No. 115,926, which contain as lubricating andcorrosion inhibiting agents a mixture of alkanolamine and carboxylicacid.

Knepp et al point out that single phase aqueous lubricants have not beenextensively used successfully in such applications as drawing, ironing,rolling, extrusion, and similar metal forming processes. However, it hasbeen customary to use certain ingredients found in synthetic lubricantssuch as, for example, oleic acid in connection with a mineral oil. Forexample, Knepp U.S. Pat. No. 3,923,671, patented Dec. 2, 1975 disclosesand claims a lubricant containing a fatty acid and mineral oil togetherwith an aliphatic carboxylic acid ester and an emulsification agent. Anemulsification agent is used to permit dispersion of the Knepp lubricantin water for use as a drawing and ironing lubricant in the can-makingart.

Knepp et al point out it is also known to use alkanolamines andpolyoxyalkylene glycols in aqueous lubricant compositions. For example,David U.S. Pat. No. 3,374,171, patented Mar. 19, 1968,discloses acutting fluid comprising an alkanolamine, a polyoxyalkylene glycol and asaturated organic acid containing from 6 to 9 carbon atoms. Davidcautions, however, against the use of higher molecular weight saturatedorganic acids stating that the use of such higher organic acids canresult in clogged filters, poor rust protection and reduced tool life inareas where hard water is encountered.

In fact, Davis describes that a balanced formulation can be obtained ina lubricant composition which is effective as a cutting fluid havingimproved corrosion-resistant lubricating and cooling efficiencyproperties and which, in the course of machining operations, maintainsits transparency in hard water solutions, avoids the formation of tackywater-insoluble residues, is free from excessive foam formation and isresistant to rancidity.

The foregoing are in general, realized with aqueous compositionscomprising a balanced formulation and containing as essential componentsa major proportion of water and, in individual minor proportions, thecombination of a saturated organic acid, either straight-chain, orbranched-chain having from about 6 to about 9 carbon atoms per molecule,a water-soluble alkanolamine and a water-soluble polyoxyalkylene glycol.In this respect, it is found that the alkanolamine component, inaddition to functioning as a corrosion-inhibiting agent in which theaforementioned organic acids are soluble, also functions as aplasticizer in that, in the course of use, evaporation of water from thecutting fluid leaves a residue upon machinery parts which is desirablysoft or semi-liquid. The function of the organic acid component incombination with the alkanolamine is primarily that of a corrosioninhibitor in that it forms the corresponding amine acid salt. Thewater-soluble polyoxyalkylene glycol in the novel composition functionsas a load-support agent.

The water-soluble alkanolamine employed in the Davis formulation may beof any molecular weight but should, preferably, be liquid at roomtemperature. The lower molecular weight compounds are generallypreferred and, for this purpose, it has been found that suchalkanolamines as mono-, di- or tri-ethanolamine are most effective.Other water-soluble alkanolamines may also be employed, and include suchalkanolamines as isopropanolamines, e.g., mono-, di- andtri-isopropanolamine, dimethyl-ethanolamine, diethyl-ethanolamine,aminoethylethanolamine, N-acetyl ethanolamine, phenylethanolamine,phenyldiethanolamine and mixtures thereof.

The organic acid component, as previously indicated, comprises asaturated organic acid, either straight-chain or branched-chain havingfrom about 6 to about 9 carbon atoms per molecule, or mixtures thereof.In this respect, it has been found that the relatively lower molecularweight acids having from about 1 to about 5 carbon atoms per molecule donot satisfactorily function as rust inhibitors and are alsoobjectionable because of their strong odor. On the other hand, it isfound that by employing relatively high molecular weight saturatedorganic acids, i.e., acids having more than about 9 carbon atoms permolecule, there results poor hard water stability, reduced corrosioninhibiting properties and high foaming tendencies. Of particular utilitywith respect to the aforementioned saturated intermediate molecularweight organic acids in the present improved formulation are hexanoic,heptanoic, caprylic and pelargonic acids.

In combination with the aforementioned water-soluble alkanolamines andsaturated organic acids is the use of the water-soluble polyoxyalkyleneglycols as load-support agents. Preferred compounds of this type includewater-soluble oils obtained by copolymerizing mixtures of ethylene oxideand propylene oxide, e.g, oils prepared by copolymerizing a 50--50mixture of ethylene oxide and propylene oxide; water-soluble hetericcopolymeric alkylene glycols, ethers or esters thereof, wherein thedifferent oxyalkylene units are substantially, randomly distributedthroughout the entire polyoxyalkylene chain; water-solublepolyoxyalkylene compounds containing hydrophobic homopolyoxyalkyleneunits; and polymeric agents, in general, which are block copolymers ofcogeneric mixtures of conjugated polyoxyalkylene compounds containing atleast one hydrophobic homopolyoxyalkylene unit, having a unit weight ofat least about 800, and one or two other hydrophilic polymeric unitswhich comprise from about 15 percent to about 90 percent of the totalpolymeric compound. The most desirable water-soluble polyxoyalkyleneglycols for use in the formulations of the David invention comprise thepolyether polyols produced by reacting ethylene oxide and propyleneoxide having hydroxyl numbers from about 22 to about 38. If so desired,in order to impart increased anti-rust properties to the aqueouslubricant composition, an alkali metal nitrite may also be employed inthe novel formulation. In this respect, it is found that more specificincreased resistance to copper corrosion may also be obtained by theadditional use of the sodium salt of mercapto-benzothiazole orbenzotriazole.

The Davis lubricant compositions are formulated in accordance withcertain balanced proportions expressed in weight percent. Thus, withwater being present in a major proportion in each instance, thealkanolamine is employed in an amount from about 5 to about 40 percent,and preferably in an amount from about 20 to about 35 percent, byweight. The organic acid component is employed in an amount from about0.1 to about 9 percent, and preferably in an amount from about 1 toabout 4 percent, by weight. The polyoxyalkylene glycol is employed in anamount from about 0.5 to about 20 percent, and preferably in an amountfrom about 0.5 to about 5 percent, by weight. If so desired, otheradditives for enhancing rust protection or for the purpose of raisingthe pH of the system may be employed. Such additional additives mayinclude boric acid or oxides of boron for enhancing rust protection, andare generally employed in an amount from about 0.1 to about 5 percent,and preferably from about 0.1 to about 3 percent, by weight. For raisingthe pH of the system, such additional additives may be employed in theform of alkali metal hydroxides, including, more specifically, sodium,lithium or potassium hydroxide. When the latter are present, they aregenerally employed in an amount from about 0.1 to about 3 percent, andpreferably from about 0.1 to about 1.5 percent, by weight. Furthermore,if so desired, various water-soluble chelating agents may be employed tosoften the water vehicle. These may include, for example, salts ofethylenediamine tetraacetic acid, nitrilo-triacetic acid or diethylenetriamine pentaacetic acid. When any of the aforementioned chelatingagents are employed, they are generally present in an amount from about0.1 to about 5 percent, by weight. In each instance, of course, it willbe apparent that sufficient water is employed in order to balance theformulation.

Davis does not disclose that these compositions can be used in themechanical working of aluminum. The alkanolamine forms the alkanolaminesalt of the organic acid, which functions as a corrosion inhibitor, as aresult, and so, to function as a plasticizer for the residues thatform,has to be used in amounts in excess of the base equivalent of theacid (which is consumed in the salt formation), to provide freealkanolamine. Since the alkanolamine is alkaline, the composition isalkaline, and is made more so by addition of alkali such as NaOH. TheDavis compositions are therefore unsuitable for mechanical working ofaluminum.

Knepp et al U.S. Pat. No. 4,243,537 discovered that a syntheticlubricant having good lubricating properties in the fabrication ofaluminum metal, particularly in the drawing and ironing of aluminumcans, can be obtained using an alkanolamine, a water-dispersible ormiscible polyoxyalkylene alcohol and an aliphatic acid containing from12 to 18 carbon atoms. A carboxylic acid ester or diester may also beused with the other ingredients. This combination of ingredientsdisperses or mixes in water to form a lubricant which has very lowextractability in hexane. In a preferred embodiment, an aliphaticcarboxylic acid ester is also added.

The alkanolamine may be a mono-, di-, or trialkanolamine wherein thealkanol moiety may have 2 to 4 carbon atoms such as ethanol, propanol,or butanol, e.g. triethanolamine.

The aliphatic acid containing from 12 to 18 carbon atoms may includeboth saturated, unsaturated, and branched chain acids and mixturesthereof. Suitable saturated and unsaturated acids include: lauric acid,myristic acid, palmitic acid, stearic acid, oleic acid, isostearic acid,linolenic acid, ricinoleic acid, etc. Preferably, the acid contains atleast 16 carbon atoms.

The polyoxyalkylene alcohol is a water-dispersing or miscible etheralcohol which is the reaction product of an alcohol or phenol withalkylene oxides. The alcohol has the formula R--OH wherein R may be a 1to 6 carbon alkyl or an aryl, including a substituted aryl. Thepolyether or polyalkylene oxide portion may comprise a polymer orethylene oxide, propylene oxide, butylene oxide, or copolymers ofcombinations of any two or all three of the above. The alkylene oxideunits in the ether may be from 2 to 20 in number.

An optional additional ingredient is an aliphatic carboxylic acid esteror diester comprising the esterified product of monocarboxylic acidshaving at least 4 carbon atoms with monoalcohols or polyhydricsincluding polyhydric polyether alcohols. The acids which have beenesterified with the alcohol may comprise only one acid or may be amixture of acids. An example of such an ester is triethylene glycolcaprate-caprylate.

In accordance with the Knepp invention, the alkanolamine should comprisefrom 5 to 15 parts by weight of the entire lubricant. The aliphatic acidshould also comprise 5 to 15 parts by weight of the lubricant. Thepolyoxyalkylene alcohol should comprise from 15 to 55 parts by weight ofthe lubricant. The aliphatic carboxylic acid ester comprises from 0 to20 parts by weight and the balance of the lubricant comprises water,i.e., from 15 to 40 parts. The foregoing ratios provide the "neat"lubricant which then is further diluted with water in actual use to theextent of from 20% by weight neat lubricant down to as little as 2% neatlubricant. The purpose of the water in the neat lubricant formulation isto provide compatibility of the constituents into a single phaseconcentrate.

The ready-to-use lubricant compositions of the Examples of U.S. Pat. No.4,243,537 thus are aqueous emulsions, which are not stable, and separateinto two phases unless stirred. In addition, mono, di andtrialkanolamines with 2 to 4 carbon alkanol groups give rise toannealing deposits that cause surface staining of aluminum. Thecompositions of EPO No. 115,926 also are unstable aqueous emulsions.

These two-phase aqueous lubricants are not satisfactory, and have notbeen accepted commercially. Their tendency to separate into two phasesimpairs their effectiveness. Their content of lubricating and corrosioninhibiting agents is so low they give poor lubrication. Because theysettle out as two phases, they deposit materials that cause stains onthe metal surfaces, which in the case of Knepp are more severe becauseof the presence of alkanolamine.

The two phase aqueous systems give rise to water-staining, so-calledwhite rust, of the aluminum surfaces, which is evidence of corrosion,showing that the components of the cooling lubricant provideinsufficient corrosion protection for aluminum. While lubrication andcorrosion protection are improved by increasing the amount of lubricantand corrosion inhibitor, at such high amounts there is obtained duringthe subsequent heat treatment an unacceptable staining of the aluminumsurface, the residues of the components of the cooling lubricant, whichare converted and burned into the aluminum surfaces.

Another problem is that roll marks and other physical damage to therolled aluminum surface may occur because metal is torn from the billetwhich is being rolled, and is welded to the rolls. The resultingirregularities during further rolling may damage the aluminum surface.

In accordance with the present invention, it has been determined thatprior water-base cooling lubricant emulsions for the mechanical workingof aluminum have been unacceptably corrosive with an insufficientlubricating effect because they were unstable, and separated into twophases, as well as too alkaline, i.e., their base/acid equivalent ratiowas above 1, and their pH was above 9, and because they caused stainingof aluminum surfaces.

In accordance with the present invention, it has been found possible toeffect cold or hot rolling of aluminum or aluminum alloys with waterbase cooling lubricants that give satisfactory lubrication and lowcorrosion without unacceptable staining of the aluminum surface duringsubsequent heat treatment. The water base cooling lubricants accordingto the present invention consist essentially of only two additives, inan aqueous solution that is stable, i.e., does not separate into twophases, at least at a temperature within the range from 20° to 70° C.:

(a) a carboxylic acid having the formula R.sub. 1COOH, in which R₁ is ahydrophobic group having from about seven to about sixteen carbon atoms;and

(b) a tertiary alkylalkanolamine having a molecular weight of less than300 and the formula ##STR1## in which:

R₂ selected from the group consisting of alkanol having from one toabout four carbon atoms and at least one hydroxyl group up to aboutthree hydroxyl groups; and (A)_(n) H wherein A is an oxyalkylene grouphaving from two to about four carbon atoms; n is a number (which can bean average number) from 1 to 3;

R₃ is an alkyl group having from one to about six carbon atoms; and

R₄ is selected from the group consisting of R₂ and R₃ ; the carboxylicacid and tertiary alkylalkanolamine being in amounts selected to give abase/acid equivalent ratio of less than 1 on the acid side of theisoelectric point.

The tertiary alkylalkanolamines differ remarkably from tertiaryalkanolamines in that they do not cause staining of the aluminumsurface.

By "stable" solution is meant that the solution does not separate intotwo or more phases within a period of at least one month.

It is essential that the base/acid equivalent ratio be less than 1 andpreferably within the range from about 0.5 to about 0.9. That is, theequivalent amount of alkylalkanolamine is less than the equivalentamount of acid. At a base/acid equivalent ratio of 1, the coolinglubricant normally has a pH below 8.5. In air the aluminum surface isoxidized and such a surface usually has an isoelectric point at apH-value of about 8.5 to 9. The compositions of the invention are soformulated that the process of mechanically working the aluminum can becarried out on the acid side of the isoelectric point, and preferably ata pH of from about 6 to about 8.

Adsorption of anions on the aluminum surface decreases, at close to theisoelectric point, and as a consequence, it is essential that thebase/acid equivalent ratio be less than 1, which means that the pH iswell below the isoelectric point, i.e., the surface is positivelycharged, and attracts anions.

Practical tests have shown that it is of great importance during rollingof the aluminum that the cooling lubricant be present in the form of astable solution, and not in separate phases as in an emulsion.Presumably, during rolling the kinetics are such that the stablesolution according to the invention quickly forms a homogeneouscontinuous adsorbed protective layer of the carboxylic acid and thetertiary alkylalkanolamine, avoiding the formation of surface depositswhich, during the subsequent heat treatment, may cause staining, andavoiding physical damage to the rolled surfaces.

A further advantage of the cooling lubricant solution according to theinvention is that it is easy to filter, in order to remove suspendedmatter formed during working. The filtered cooling lubricant may bereused without appreciable risk of staining, metal-catalyzed oxidativedegradation, or microbial degradation.

No active ingredients other than the carboxylic acid (a) and thetertiary alkylalkanolamine (b) and water are essential.

The hydrophobic group R₁ of the carboxylic acid R₁ COOH is preferably astraight chain saturated aliphatic hydrocarbon group, having from aboutseven to about sixteen carbon atoms, although branched unsaturatedaliphatic hydrocarbon groups are also useful. Especially preferred arealkyl groups having from about seven to about eleven carbon atoms.Specific examples of suitable carboxylic acids are pelargonic acid,heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoicacid, lauric acid, myristic acid, palmitic acid, and mixtures thereof,such as the mixed fatty acids derived from fats and oils that arepredominantly acids of sixteen carbon atoms or less, such as coconut oilfatty acids.

The hydrophobic group R₁ may also contain hetero atoms, such as oxygen,sulphur and nitrogen, which are included in such functional groups asether, thioether, ester, hydroxyl, carboxyl, and amide groups. Examplesof such carboxylic acids are ##STR2## wherein R₈ is alkyl having fromone to about four carbon atoms or hydrogen, and R.sub. 7 is ahydrocarbon group, preferably an aliphatic hydrocarbon group, havingfrom five to sixteen carbon atoms, R₇ and R₈ being selected such thatthe total number of carbon atoms in R₁ is within the range stated.

Exemplary R₂ alkanol groups of the tertiary alkylalkanolamine includehydroxymethyl, hydroxyethyl, hydroxy propyl, hydroxy isopropyl, hydroxybutyl, hydroxy isobutyl, hydroxy tertiary butyl, dihydroxy propyl,dihydroxy isopropyl, dihydroxy butyl, dihydroxy isobutyl, and trihydroxybutyl.

Exemplary R₃ alkyl include methyl, ethyl, propyl, isopropyl, butyl,isobutyl, sec-butyl, tert-butyl, amyl, isoamyl, sec-amyl, tert-amyl,hexyl, isohexyl, tert-hexyl and sec-hexyl.

Examples of suitable tertiary alkylalkanolamines are diethanol ethylamine, diethanol propyl amine, diethanol butyl amine, diethanol pentylamine, diethanol hexyl amine and the corresponding dipropanol amines,ethanol diethyl amine, ethanol dipropyl amine, ethanol dibutyl amine andthe corresponding propanol amines, and such alkanolamines containing(A)_(n) H groups derived from ethylene oxide, propylene oxide, butyleneoxide, and mixtures thereof.

The amount of carboxylic acid and tertiary alkylalkanolamine is selectedso as to give a base/acid equivalent ratio below 1, and preferablywithin the range from about 0.5 to about 0.9, which results in a coolinglubricant having a pH within the range from about 6 to about 8. Lowratios of alkanolamine to carboxylic acid give an improved lubricatingeffect. Good lubrication is obtained at base/acid equivalent ratios offrom 0.5 up to about 0.8.

In addition to the alkylalkanolamine and carboxylic acid, which are theessential ingredients, the compositions of the invention optionally butpreferably also include a nonionic compound (c). The nonionic compound(c) primarily contributes to the lubricating effect of the coolinglubricant, and must be predominantly hydrophobic in character. By thisis meant that it should have a HLB value of less than 10, preferablyless than 9. The preferred nonionic compounds are relatively insolublein water, but dissolve in the aqueous solution of (a) and (b).

The nonionic compound (c) can be selected from aliphatic nonioniccompounds; aromatic nonionic compounds; and mixed aliphatic aromaticnonionic compounds. The aliphatic compounds are preferred.

Suitable nonionic compounds (c) have the formula R₅ (B)_(m) OR₆, whereinR₅ is a hydrocarbon or acyl group having from about eight to abouttwenty-four carbon atoms, B represents an oxyalkylene group having fromtwo to four carbon atoms, R₆ is hydrogen, or an alkyl or acyl grouphaving from one to four carbon atoms, and m is a number (which can be anaverage number) from 0 to 4.

Examples of preferred nonionic compounds of this formula, where R₆ is H,are water-insoluble alcohols, such as octanol, decanol, dodecanol,tetradecanol, hexadecanol, and octadecanol; oxo alcohols having fromnine to seventeen carbon atoms; phenols such as nonyl phenol, octylphenol, and dodecyl phenol, as well as ethoxylates of the abovementioned alcohols and phenols with from 1 to 4 moles of ethylene oxideper mole of alcohol or phenol. These compounds are defined by thegeneral formula R₅ (B)_(m) OH, where R₅, B, and m have the meaningsindicated above.

Other examples of nonionic compounds are fatty acid esters which arealkoxylated or esterified with the compound H(B)_(m) OR₆, wherein B, R₆,and m have the meaning indicated above. Specific examples of this typeare C₁₁ H₂₁ COOC₂ H₄ OH; C₁₁ H₂₃ COOCH₃ ; C₉ H₁₉ CO(OC₂ H₄)₂ OCH_(R) ₅(B)_(m) OR₆, where R₅ is acyl as above.

Preferred esters are those having the general formula R₅ OR₆, wherein R₅is an acyl group having from eight to twenty-four carbon atoms, andR.sub. 6 is an alkyl group having from one to four carbon atoms.

Examples of compounds of the above formula where B is an oxyalkylenegroup and m is 1 to 4 are polymers based on ethylene oxide and higheralkylene oxides. The alkylene oxide units may be both random-coupled andcoupled in blocks.

In addition to the above mentioned components (a), (b), and (c), theaqueous cooling lubricant solutions according to the invention may alsocontain conventional additives that are soluble therein, such asbactericidal agents, antifoam additives, viscosity controlling agents,perfumes, and additional agents capable of supplementing lubrication andcorrosion protection.

In accordance with the invention, concentrates are provided that upondilution with water form a ready-to-use cooling lubricant and containthe following ingredients:

    ______________________________________                                                      Proportion (% by weight)                                        Ingredient      overall range                                                                            preferred range                                    ______________________________________                                        Carboxylic acid 15 to 75   20 to 45                                           Tertiary        3 to 60    10 to 45                                           alkylalkanolamine                                                             Nonionic compound                                                                             0 to 10    1 to 5                                             Additives:                                                                    bactericidal agents,                                                                          0 to 30     0 to 15                                           perfumes, viscosity                                                           controlling agents etc.                                                       Water           0 to 82     0 to 69                                           ______________________________________                                    

The cooling lubricants obtained after diluting the concentrate withwater and ready for use have the composition:

    ______________________________________                                                     Proportion (% by weight)                                         Ingredient     overall range                                                                            preferred range                                     ______________________________________                                        Carboxylic acid                                                                              0.5 to 25  2 to 15                                             Tertiary       0.1 to 20  1 to 15                                             alkylalkanolamine                                                             Nonionic compound                                                                            0 to 4     0.2 to 2                                            Additives:                                                                    bactericidal, agents,                                                                        0 to 5     0.1 to 2                                            perfumes, viscosity                                                           controlled agents                                                             Water            25 to 99.4                                                                              40 to 96.7                                         ______________________________________                                    

The cooling lubricant when ready for use preferably has a water contentwithin the range from 70 to 95% by weight.

The cooling lubricant is applied to the aluminum sheet during mechanicalworking in the usual way, as a spray or by dipping or using a wick ordoctor blade, to provide cooling and lubrication during the working. Thecooling lubricants of the invention are of practical application in thecold rolling of annealed aluminum sheets using a standard rolling mill.The method and apparatus form no part of the instant invention, and arewell known to those skilled in this art.

The following Examples represent preferred embodiments of the invention:

Examples 1 to 5

The following cooling lubricant concentrates according to the inventionwere prepared. All were stable concentrate solutions at 20° C.

                  TABLE I                                                         ______________________________________                                        Example   Formulation      Parts by Weight                                    ______________________________________                                        1         Lauric acid      8.56                                                         C.sub.4 H.sub.9 N(C.sub.2 H.sub.4 OH).sub.2                                                    6.44                                                         Base/acid equivalent ratio                                                                     0.93                                               2         Lauric acid      12.0                                                         C.sub.4 H.sub.9 N(C.sub.2 H.sub.4 OH).sub.2                                                    8.0                                                          Base/acid equivalent ratio                                                                     0.83                                                         Pelargonic acid  8.62                                                         C.sub.4 H.sub.9 H(C.sub.2 H.sub.4 OH).sub.2                                                    6.38                                                         Base/acid equivalent ratio                                                                     0.72                                               4         Decanoic acid    11.26                                                        2,2-Dimethylamino methyl                                                                       5.36                                                         propanol                                                                      Base/acid equivalent ratio                                                                     0.70                                               5         Lauric acid      8.51                                                         C.sub.4 H.sub.9 N(C.sub.2 H.sub.4 OH).sub.2                                                    6.34                                                         C.sub.12-14 H.sub.25-29 OH                                                                     0.14                                                         Base/acid equivalent ratio                                                                     0.93                                               ______________________________________                                    

The above lubricant concentrates are stable solutions that are dilutedwith from 25 to 75 parts of water to form ready-to-use cooling lubricantsolutions in accordance with the invention.

For comparison, the following cooling lubricants were prepared. All werein the form of aqueous emulsions over the entire temperature range of20° to 70° C. The cooling lubricants in accordance with U.S. Pat. No.4,243,537 are Controls A, B and C, while cooling lubricants formulatedin accordance with EPO Patent Application No. 115,926 are Controls D andE.

                  TABLE II                                                        ______________________________________                                        Control Formulation      Percent by Weight                                    ______________________________________                                        A       Oleic acid       2                                                            Triethanol amine 1                                                            Polyalkylene glycol                                                                            10                                                           (UCON 5HB 100)                                                                Water            balance                                                      Base/acid equivalent ratio                                                                     0.95                                                         pH                                                                    B       Oleic acid       2                                                            Triethanol amine 1                                                            Polyalkylene glycol                                                                            10                                                           (UCON 5HB 100)                                                                 ##STR3##        3                                                            Water            balance                                                      Base/acid equivalent ratio                                                                     0.95                                                         pH                                                                    C       Oleic acid       2.0                                                          Triethanol amine 1.6                                                          Polyalkylene glycol                                                                            10                                                           (UCON 5HB 100)                                                                Water            balance                                                      Base/acid equivalent ratio                                                                     1.5                                                          pH                                                                    D       Lauric acid      1.5                                                          Diethanol amine  1.5                                                          Polyalkylene glycol                                                                            10                                                           (Pluronic 17R2)                                                                ##STR4##        1.0                                                          Water            balance                                                      Base/acid equivalent ratio                                                                     1.9                                                          pH                                                                    E       Oleic acid       1.0                                                          Triethanol amine 0.8                                                          Polyalkylene glycol                                                                            5.0                                                          (Pluronic 17R2)                                                               Water            balance                                                      Base/acid equivalent ratio                                                                     1.5                                                          pH                                                                    ______________________________________                                    

All of the above lubricant concentrates of Examples 1 to 5 were dilutedwith water to form ready-to-use cooling lubricants in which the totalwater was the balance computing the remaining ingredients as % byweight, instead of the parts by weight in Examples 1 to 5.

Cold rolling of annealed aluminum sheet of grade AA3004 was carried outusing these cooling lubricants and the Controls in a single stand withrolls having a diameter of 159 mm. During rolling, the sheet thicknesswas reduced from 1.05 mm to 0.63 mm. The requisite rolling force wasdetermined as the pressure in the hydraulic system transferring thecompressive force to the rolls. After rolling, the surfaces were judgedvisually with respect to physical damage on a scale from 0 to 1. Thevalue 0 designates a surface which is up to standard, i.e. a surfaceessentially free from physical damage, while 1 designates a surface notup to standard, i.e. a surface with visible physical damage.

The rolled aluminum sheets were wiped clean and supplied with coolinglubricant in abundance, whereupon another sheet was placed on top andboth sheets were heated to 360° C. for five hours in air. The appearanceafter heating was judged visually with respect to color, i.e., thedegree of blackening, on a scale from 0 to 4, and the proportion ofstained surface as % of the whole surface area.

    ______________________________________                                        Scale     Color        Stained surface, %                                     ______________________________________                                        0         Perfect no color                                                                           0                                                      1         Discernible color                                                                          1-15                                                   2         Slight color 6-15                                                   3         Distinct color                                                                             16-50                                                  4         Strong color 51-100                                                 ______________________________________                                    

The color and stained surface were summed up as a total assessmentdesignated "annealing residues" on a scale of from 0 to 8, in which 0 to1 is excellent, 2 to 3 well up to standard, 4 to 5 just up to standard,and 6 to 8 below standard. By "just up to standard" is meant that thealuminum sheets would be just commercially acceptable.

In order to determine the corrosive effect of the cooling lubricant uponiron, cast-iron chips were placed on a filter paper that had been soakedwith a specific amount of the cooling lubricant and left for 24 hours.Then a grid having 126 intersections over an area of 150 cm² was placedover the filter paper, and the occurrence of corrosion was determinedfor each point of intersection on the grid. The iron corrosion was thenexpressed as the number of intersecting points with rust in relation tothe total number of intersecting points.

White rust was determined by coating aluminum sheets with the coolinglubricant, and then stacking the sheets and cooling them for 1 hour at-b 20° C., whereupon they were exposed for 2 hours to humid air of roomtemperature. After that, the sheets were heated to 80° C. for 10 hours.The white rust was then assessed in the same manner as the ironcorrosion.

The following results were obtained:

                  TABLE III                                                       ______________________________________                                        Example                                                                              Force   Annealing Iron   White  Physical                               No.    kN      residues  corrosion                                                                            rust % appearance                             ______________________________________                                        Control                                                                       A      13.3    5         5      20     1                                      B      13.5    8         4      6      1                                      C      14.0    8         0.1    12     1                                      D      16.5    5         0      0      1                                      E      14.5    5         4      30     1                                      Example                                                                       1      13.5    3         0      0      0                                      2      13.5    3         0      0      0                                      3      13.5    2         0      0      0                                      4      13.0    3         0      0      0                                      5      13.2    3         0      0      0                                      ______________________________________                                    

As is evident from these results, the cooling lubricants according tothe invention provide, as compared with the prior art Controls A to E,rolled aluminum surfaces having a far better physical appearance. Ironcorrosion and white rust both are maintained at a very low level, whichis essentially lower than for the controls. In addition, the coolinglubricants according to the invention give a low level of annealingresidues, which in all cases are essentially lower than the controls.

Having regard to the foregoing disclosure, the following is claimed asthe inventive and patentable embodiments thereof:
 1. An aqueous stablecooling lubricant solution that does not separate into two phases at atemperature within the range from 20° to 70° C., over a period of atleast one month for use in the mechanical working of aluminum andaluminum alloys, that gives satisfactory lubrication and low corrosionwithout unacceptable staining of the aluminum surface during subsequentheat treatment, and consisting essentially of(a) a carboxylic acidhaving the formula R₁ COOH, in which R₁ is a hydrophobic group havingfrom about seven to about sixteen carbon atoms selected from the groupconsisting of aliphatic hydrocarbon and aliphatic hydrocarbon includinga group selected from ether, thioether, ester, hydroxyl, carboxyl, andamide and (b) a tertiary alkylalkanolamine having a molecular weight ofless than 300 and the formula ##STR5## in which: R₂ is selected from thegroup consisting of alkanol having from one to about four carbon atomsand at least one hydroxyl group up to about three hydroxyl groups; and(A)_(n) H wherein A is an oxyalkylene group having from two to aboutfour carbon atoms; n is a number (which can be an average number) from 1to 3;R₃ is an alkyl group having from one to about six carbon atoms; andR₄ is selected from the group consisting of R₂ and R₃ ; the carboxylicacid and tertiary alkylalkanolamine being in amounts selected to give abase/acid equivalent ratio of less than 1 on the acid side of theisoelectric point; and (c) water; the carboxylic acid (a) and thetertiary alkyl alkanolamine (b), and their amounts being so selected asto give a stable aqueous solution when water is present in a selectedworking concentration of water within the range from about 25 to about99.4%.
 2. An aqueous stable cooling lubricant solution according toclaim 1 in which the base/acid equivalent ratio is within the range fromabout 0.5 to about 0.9.
 3. An aqueous stable cooling lubricant solutionaccording to claim 1, in which R₁ of the carboxylic acid R₁ COOH is astraight chain saturated aliphatic hydrocarbon group having from aboutseven to about eleven carbon atoms.
 4. An aqueous stable coolinglubricant solution according to claim 1, in which the carboxylic acidR.sub. 1COOH is selected from the group consisting of ##STR6## whereinR₈ is alkyl having from one to about four carbon atoms or hydrogen, andR₇ is a hydrocarbon group, having from five to twenty carbon atoms, R₇and R₈ being selected such that the total number of carbon atoms in R₁is within the range stated.
 5. An aqueous stable cooling lubricantsolution according to claim 1, in which the tertiary alkylalkanolamineis selected from the group consisting of diethanol ethyl amine,diethanol propyl amine, diethanol butyl amine, diethanol pentyl amine,diethanol hexyl amine and the corresponding dipropanol amines, ethanoldiethyl amine, ethanol dipropyl amine, ethanol dibutyl amine and thecorresponding propanol amines, and such alkanolamines containing A₂groups derived from ethylene oxide, propylene oxide, butylene oxide, andmixtures thereof.
 6. An aqueous stable cooling lubricant solutionaccording to claim 1, in which the solution is in the form of aconcentrate containing up to 70% water, and upon dilution with waterforms a ready-to-use cooling lubricant.
 7. An aqueous stable coolinglubricant solution according to claim 6 having the followingformulation:

    ______________________________________                                        Ingredient       Proportion (% by Weight)                                     ______________________________________                                        Carboxylic acid  15 to 75                                                     Tertiary alkylalkanolamine                                                                     3 to 60                                                      Additives:                                                                    bactericidal agents, perfumes,                                                                 0 to 30                                                      viscosity controlling agents etc.                                             Water            0 to 82                                                      ______________________________________                                    


8. An aqueous stable cooling lubricant solution according to claim 6having the following formulation:

    ______________________________________                                        Ingredient       Proportion (% by Weight)                                     ______________________________________                                        Carboxylic acid  20 to 45                                                     Tertiary alkylalkanolamine                                                                     10 to 45                                                     Additives:                                                                    bactericidal agents, perfumes,                                                                  0 to 15                                                     viscosity controlling agents etc.                                             Water             0 to 69                                                     ______________________________________                                    


9. An aqueous stable cooling lubricant solution according to claim 1,having the following formulation:

    ______________________________________                                        Ingredient       Proportion (% by Weight)                                     ______________________________________                                        Carboxylic acid  0.5 to 25                                                    Tertiary alkylalkanolamine                                                                     0.1 to 20                                                    Additives:                                                                    bactericidal agents, perfumes,                                                                  0 to 5                                                      viscosity controlled agents                                                   Water              25 to 99.4                                                 ______________________________________                                    


10. An aqueous stable cooling lubricant solution according to claim 1,having the following formulation:

    ______________________________________                                        Ingredient       Proportion (% by Weight)                                     ______________________________________                                        Carboxylic acid  2 to 15                                                      Tertiary alkylalkanolamine                                                                     1 to 15                                                      Additives:                                                                    bactericidal agents, perfumes,                                                                 0.1 to 2                                                     viscosity controlled agents                                                   Water             40 to 96.7                                                  ______________________________________                                    


11. An aqueous stable cooling lubricant solution according to claim 1,including in addition a nonionic compound having the formula R₅ (B)_(m)OR₆, wherein R₅ is selected from the group consisting of hydrocarbon andacyl groups having from about eight to about twenty-four carbon atoms, Bis an oxyalkylene group having from two to four carbon atoms, R₆ isselected from the group consisting of hydrogen and alkyl and acyl groupshaving from one to four carbon atoms, and m is a number (which can be anaverage number) from 0 to
 4. 12. An aqueous stable cooling lubricantsolution according to claim 11 in which the anionic compound has thegeneral formula R₅ (B)_(m) OH, wherein R₅, B and m have the meaningsindicated in claim
 11. 13. An aqueous stable cooling lubricant solutionaccording to claim 11 wherein the nonionic compound is selected from thegroup consisting of water-insoluble alcohols, and oxo alcohols havingfrom nine to seventeen carbon atoms; phenols; and ethoxylates of suchalcohols and phenols with from 1 to 4 moles of ethylene oxide per moleof alcohol or phenol.
 14. An aqueous stable cooling lubricant solutionaccording to claim 11 in which the nonionic compound is a fatty acidester which is alkoxylated or esterified with the compound H(B)_(m) OR₆,and has the formula R₅ (B)_(m) OR₆, wherein R₅ is acyl and wherein B,R₆, and m have the meaning indicated in claim
 11. 15. An aqueous stablecooling lubricant solution according to claim 11 having the followingformulation:

    ______________________________________                                        Ingredient       Proportion (% by Weight)                                     ______________________________________                                        Carboxylic acid  15 to 75                                                     Tertiary alkylalkanolamine                                                                     3 to 60                                                      Nonionic compound                                                                              0.1 to 10                                                    Additives:                                                                    bactericidal agents, perfumes,                                                                 0 to 30                                                      viscosity controlling agents etc.                                             Water            0 to 82                                                      ______________________________________                                    


16. An aqueous stable cooling lubricant solution according to claim 11having the following formulation:

    ______________________________________                                        Ingredient       Proportion (% by Weight)                                     ______________________________________                                        Carboxylic acid  20 to 45                                                     Tertiary alkylalkanolamine                                                                     10 to 45                                                     Nonionic compound                                                                              1 to 5                                                       Additives:                                                                    bactericidal agents, perfumes,                                                                  0 to 15                                                     viscosity controlling agents etc.                                             Water             0 to 69                                                     ______________________________________                                    


17. An aqueous stable cooling lubricant solution according to claim 11having the following formulation:

    ______________________________________                                        Ingredient       Proportion (% by Weight)                                     ______________________________________                                        Carboxylic acid  0.5 to 25                                                    Tertiary alkylalkanolamine                                                                     0.1 to 20                                                    Nonionic compound                                                                              0.1 to 4                                                     Additives:                                                                    bactericidal agents, perfumes,                                                                  0 to 5                                                      viscosity controlled agents                                                   Water              25 to 99.4                                                 ______________________________________                                    


18. An aqueous stable cooling lubricant solution according to claim 11having the following formulation:

    ______________________________________                                        Ingredient       Proportion (% by Weight)                                     ______________________________________                                        Carboxylic acid  2 to 15                                                      Tertiary alkylalkanolamine                                                                     1 to 15                                                      Nonionic compound                                                                              0.2 to 2                                                     Additives:                                                                    bactericidal agents, perfumes,                                                                 0.1 to 2                                                     viscosity controlled agents                                                   Water             40 to 96.7                                                  ______________________________________                                    


19. A process for the mechanical working of aluminum and aluminumalloys, which comprises mechanically working the aluminum or aluminumalloy in the presence of an aqueous stable cooling lubricant solutionaccording to claim
 1. 20. A process according to claim 19, in which themechanical working is rolling at a temperature within the range fromabout 20° to about 70° C.
 21. A process for the mechanical working ofaluminum and aluminum alloys, which comprises mechanically working thealuminum or aluminum alloy in the presence of an aqueous stable coolinglubricant solution according to claim
 9. 22. A process for themechanical working of aluminum and aluminum alloys, which comprisesmechanically working the aluminum or aluminum alloy in the presence ofan aqueous stable cooling lubricant solution according to claim
 10. 23.A process for the mechanical working of aluminum and aluminum alloys,which comprises mechanically working the aluminum or aluminum alloy inthe presence of an aqueous stable cooling lubricant solution accordingto claim
 11. 24. A process according to claim 23, in which themechanical working is rolling at a temperature within the range fromabout 20° to about 70° C.
 25. A process for the mechanical working ofaluminum and aluminum alloys, which comprises mechanically working thealuminum or aluminum alloy in the presence of an aqueous stable coolinglubricant solution according to claim
 17. 26. A process for themechanical working of aluminum and aluminum alloys, which comprisesmechanically working the aluminum or aluminum alloy in the presence ofan aqueous stable cooling lubricant solution according to claim 18.